4 3
A power station burns methane, CH4. (a) Construct a balanced symbol equation for the complete combustion of methane.
.............................................................................................................................................. [2] (b) The power station produces nitrogen dioxide gas. The owners need to stop the nitrogen dioxide going into the atmosphere. They can choose two methods: •
use limestone
•
use sea water.
Look at the table. It shows some information about each method. Limestone
Sea water
90%
99%
Percentage of nitrogen dioxide removed Waste made
carbon dioxide and a solid waste product
none – sea water is pumped back into the sea
Cost
expensive
cheap
Availability
mined from under the ground
must be pumped in from the coast
Mass needed to remove 1 g of nitrogen dioxide
1.2 g
3000 g
The power station is 100 kilometres from the coast. The power station makes 9000 g of nitrogen dioxide. Which method would be more suitable for removing nitrogen dioxide from the waste gases? Explain your answer. ................................................................................................................................................... ................................................................................................................................................... ................................................................................................................................................... .............................................................................................................................................. [2] [Total: 4]
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